Synonyms

Historical Background

Natural Killer (NK) cells are a major component of the innate immune system, providing surveillance against infected or transformed cells without the requirement of prior host sensitization. NK cells were first discovered by their cytotoxic potency against tumor cells (Kiessling et al. 1975), and their importance was demonstrated early on in herpes viral infections, usually mild or localized, which become severe and life-threatening in NK-deficient patients. NK cell effector functions are governed by the balance of potentially opposing signals from a diverse array of both activating and inhibitory receptors on the cell surface that are not rearranged from germ-line receptor segments, unlike B and T cell receptors (BCRs, TCRs) on lymphocytes. While NK cells are now well characterized in terms of their...